Glass insulator and method of making same



Nov. 4, 193%. D. H. ROWLAND GLASS INSULATOR AND METHOD OF' MAKING SAME Filed Dec. 9, 1924 v\\\\\ \v\\\\\ m xA N n J TIE;

Patented Nov. 4, 1930 UNITED STATES PATENT' @FFlCE DAVIDGEH. BOWLAND, OF BALTIMORE, MARYLAND, ASSIGNOR T LOCKE INSULATOB CORPORATION, OF BALTIMORE, MARYLAND, A CORPORATION 0F MARYLAND GLASS INSULATOR AND METHOD OF MAKING SAME Application tiled December 9, 1924. Serial No. 754,746.

The invention relates to glass insulators land methods of making the same.

The primary object of the invention, generally considered, is to provide a method ot making Hewlett type insulators of glass.

Ordinarily, insulators of this type are made of porcelainor other vitreous material and while the molded insulator is still in a somewhat plastic condition curved holes are out therethrough, whichholes or passages inter- 2o the pin type have been made of glass with' link and are intended for the reception of suspension and connecting elements whereby a series of units may be connected together to form a string. In making an insulator of this type of glass itis obvious that it is impossible to cut the curved holes or passages tor thereception of the suspension elements and it becomes necessary to resort to some other expedient. I am aware that insulators of the pin embedded therein but inall cases where a metallic elementis tightly embedded within glass there are severe strains and stresses set up on account of the dliference 1n the coelicients of expansion of'metal and l glass, and during extreme changes in temperature conditions the glass frequently breaks. The object of the present invention more specificall stated, i's to provide a method of making ewlett type insulators of glass and in which the suspension elements are loosely mounted or embedded, the carrying out of the method involving the application ofy heat to or the generation of heat within the metallic suspension elements whereby they will he caused to expand to an appreciable extent while the glass is being molded about them so that upon subsequent cooling and shrinkage of the insulator the suspension elements will fit within the holes or passages with suflicient loosenessthat any ordinary temperature changes to which the unit ma be subjected in service will not cause su cientexpansion to result in binding of the suspension elements within the insulator body, `this looseness also permitting the successivel units of a string to accommodate themselves automatically to the line of tension so that they will he arranged co-axially when 1n depending condition. i

in which the metallic suspension elements` may be permanently though loosely mounted so that they will always be in place ready for connection by appropriate means to form a string.

Broadly speaking, the method consists n molding a glass body about interlinking suspension links or members held in proper relation, the links or suspension members having the temperature thereof raised 'referably to a point suicient to expand tliem so that upon cooling and shrinking they will fit loosely within the bod While various means may be employed or carrying out the method, I have, for the sake of clearness, disclosed a suitable means illustrated in the accompanying drawings, in which:

Figure l is a cross section through a suitable mold, illustrating the method of making an insulator in accordance with my invention.

Figure 2 is a plan view.

Throughout the specification and drawings like parts are designated by like reference characters.

Referring to the drawings in detail, the numerals 1 and 2 designate suitable mold elements or members having their confronti faces recessed and shaped, as shown at 3 an 4, respectively, to correspond to the u per and lower surfaces of the'type of insu ator to be made. The articular configuration disclosed is merely or illustrative purposes as it is obvious that variations may be made therein if desired. The mold elements may, themselves, be of any size and shape, depending upon circumstances, and may be constructed of the usual or any preferred material appropriate for the purpose. The mold members are relatively Imovable and one,

preferably the lower, is stationary and serves vas a support.

ylinks within the body7 ber 2 is formed with holes 9 through which pass the arms of another similar suspension element 10 which is located at right angles to the member 6 and which has its bight portion 11 projecting into the cavity 8 and interlinking with the bight portion 7 ofthe member 6 but in -spaced relation thereto. Any suitable means maybe provided for suspending the member 10 in proper position, and for the sake of illustration I have shown` notched or slotted blocks 12 ontop of the member 2 engaging beneath heads 13 on the ends of the arms of the member 10, which heads may have an desired configuration and which are provided for the purpose of engagement with suitable connecting elements, not shown, whereby the suspension members of successive units may be connected to form a string.

An important feature involved 'in my method is'the heating of the members 6 and 10 prior to or while the glass insulator body 14 is moldedin the cavity 8 in embedding relation to these members. Obviously, this might be carried out in any one of various wa s though a convenient method is to pro- -vi e conducting members 15 within the lower mold member 1 at the bottoms of the holes 5 so that the arms of the member 6 will rest upon them. The members 12 are likewise conductors.v Current may be supplied to the membersl and 12 so that the resistance of the suspension members to the passage of the current will result in generation of heat. In actual practice the suspension members wil] probably be heated to redness while the glass body is molded in the cavity. While .any means might be provided for introducing or permitting the introduction of the molten glass within the cavity8, I have shown the upper mold member as provided with an opening 16 through which the glass may be poured. After cooling, the members 12 are removed, the mold member 2 lifted off and then the molded insulator with the links therein lifted out. On account of the shrinkageoccurring during cooling, the suspension members or links will fit loosely within the body and any rise in temperature which may occur in service will be lnsuicient to causev expansiony of the suspension members to such an extent as to cause them to bind within the .c body. Likewise, a decrease in temperature will have no injurious eifect. Owing to the fact that the embedding of the suspension forms the curved interlinking passages, 1t is a parent that the walls of these passages con orm to the shape of the links and in this way a smooth bearing surface is provided which will avoid the bringing of any undue strain upon the body of the insulator due to high spots withinthe assages. The suspension links might be ma e of such .shape as to be capable of subsequent withdrawal from the passages Athe suspension link until after the though it may be preferable to have them of such construction and shape as to remain permanently attached tojthe insulator body though loose with respect thereto, such variations and modifications being within the sco e of the invention.

bviously, the mold members may each be formed of any desired number of parts and the material may be of anynature suitable for the purpose, though if the mold be metallic or of other conducting material, it would naturally be necessary to provide some means for insulating the links and lcontacts or terminals'from the body of the mold. Having now described my invention, what I claim is:

1. The method of making an yinsulator equipped with suspension means, consisting v in molding the glass about suspension elements and at the same time 'apply-ing heat to the suspension elements for effecting expansion thereof until the glass has set.

2. The method of making a glass insulator equipped with inte'rlinking suspension means,

consisting in molding a glass bodyabout the sulator of a type equipped with a suspension member, consisting in molding a glass body about a suspension member and continuously heating the suspension member until after the glass has set.

5. The method of making of glass an in sulator of the suspension type and equipped with a curved suspension link, consisting 1n molding a glass body about a 'suspensionlink whereby the link will be partially embeddedA within the body, and'heating the link until after the glass has set. 6. The method of making of` glass van insulator of the suspension type and equipped' with a curved suspension link, consisting 1n v molding a glass body `about a suspension link whereby the link will be partially embedded within the body, Vand continuously heating glass has ceased to flow.

7. The method of making a suspension insulatorl of glass, consisting in' interlinking suspension members, molding a glass. body about the members to embed the interlinking .portions thereof, and heating said members during the molding and until after the glass Y has lost its plasticity.

8. The method of making a glass suspension insulator, consisting in arranging curved suspension members in interlinking relation, heating said members and at the same timev molding a glass body about the interlinking portions of said members, and continuing the heating of said members until after the glass has set.

9. The method of making an insulator of a type having a permanently attached suspension element, comprising molding a glass body about said suspension element and passing an electric current through the element to effect heating thereof during molding, and continuing said heating until after the glass has set. y

l0. The method of making an insulator of a type having a sus ension element permanently carried thereby, comprising expanding the suspension element, casting vitreous material about a portion of the element, and maintaining the expanded condition of the element until after the vitreous material has lost its plasticity. In testimony whereof I aiiix my signature.

DAVIDGE H. ROVVLAND. 

